Oversize tyres

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DACA
Posts: 10
Joined: Sun Jun 28, 2015 7:31 am

Post by DACA »

Does anyone know if 235:55r 19 can be fitted to qq tekna and ecru altered to reflect change in size. The error margin is not too high without the change. anyone any ideas about handling?
DACA

Ink Blue 1.6 DCi Tekna Xtronic

gvmdaddy
Posts: 2245
Joined: Thu Jun 19, 2014 11:28 pm

Post by gvmdaddy »

I asked this question a couple of years back and never got a response. I was looking at doing it to increase the latteral overhang of the tyre compared to the rim to offer more protection against kerbing. I also asked if it posed a legal issue.
Deleted User 3871

Post by Deleted User 3871 »

I increased the profile on my mini coupe by 10 with no problems what so ever. The ride is softer now which is what I was after & the speedo reads only slightly slower. ie when doing 60mph on the clock im doing about 58mph true. win win.
gvmdaddy wrote:I asked this question a couple of years back and never got a response. I was looking at doing it to increase the latteral overhang of the tyre compared to the rim to offer more protection against kerbing. I also asked if it posed a legal issue.
gvmdaddy
Posts: 2245
Joined: Thu Jun 19, 2014 11:28 pm

Post by gvmdaddy »

Daewar wrote:I increased the profile on my mini coupe by 10 with no problems what so ever. The ride is softer now which is what I was after & the speedo reads only slightly slower. ie when doing 60mph on the clock im doing about 58mph true. win win.
gvmdaddy wrote:I asked this question a couple of years back and never got a response. I was looking at doing it to increase the latteral overhang of the tyre compared to the rim to offer more protection against kerbing. I also asked if it posed a legal issue.
Surely, increase the diameter you increase the speed.
Deleted User 3871

Post by Deleted User 3871 »

GVM,

I should have been clearer. I meant the speedo reads only slightly slower than true speed. At 60mph speedo, the car now reads about 58mph true. So in effect, its actually more accurate.

Im unsure how the MPG figure is affected, its probably so small it makes no difference.
gvmdaddy wrote: Surely, increase the diameter you increase the speed.
gvmdaddy
Posts: 2245
Joined: Thu Jun 19, 2014 11:28 pm

Post by gvmdaddy »

I presume with a lot of stop/start town driving the acceleration would be slower and fuel consumption greater, but long runs would be more fuel efficient.....a bit like pedaling a bmx bike or one of Sir Bradley Wiggins road bikes!
Thrall
Posts: 83
Joined: Wed Apr 27, 2016 4:44 pm
Location: Reykjavik, Iceland

Post by Thrall »

I changed from 215/60 R17 to 215/65 R17, which raised the car very slightly, corrected the 2% error on the odometer and made the wildly optimistic speedometer slightly more accurate. I found no change in fuel consumption or in driving characteristics, but probably bumps are very slightly better absorbed. Are tyre sizes ever checked in a MOT? Here, small changes are tolerated in tyre size and height of car, up to 1.5 inches I think.
2013 J10 SE 1.6 dCi 6speed manual, 4wd.
Deleted User 3871

Post by Deleted User 3871 »

There is a check, but from what I can understand, its to make sure you have the same wheel size on the same axle. A lot of sports cars have wider wheels at the rear compared to the front wheels, i.e. rear wheel drive.

https://www.gov.uk/government/publicati ... -at-an-mot

2.12 Tyres and wheels
These will be inspected to check for:

condition
security
tyre size and type
tread depth
Spare wheels and tyres are not inspected.


Thrall wrote:I changed from 215/60 R17 to 215/65 R17, which raised the car very slightly, corrected the 2% error on the odometer and made the wildly optimistic speedometer slightly more accurate. I found no change in fuel consumption or in driving characteristics, but probably bumps are very slightly better absorbed. Are tyre sizes ever checked in a MOT? Here, small changes are tolerated in tyre size and height of car, up to 1.5 inches I think.
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